This invention relates to techniques in the separation sciences and more particularly to techniques for collecting separated sepcimen, such as for example, the type of collecting performed by apparatus known as fraction collectors.
It is known in the separation sciences to automatically collect materials separated by a separating apparatus. One type of such separating apparatus performs separation by electrophoresis and is known as an electrophoresis apparatus. In this process, the samples are separated in a medium as the molecular species are moved through the medium under the influence of an electrical potential.
One class of electrophoresis apparatus is a capillary electrophoresis apparatus. In a capillary electrophoresis apparatus, the medium is in a small diameter capillary tube. This tube is usually made of fused quartz. The electrophoresis medium may be a gel or liquid in capillary electrophoresis. The separated bands or zones of molecular species are sensed by a detector that transmits light through the medium and senses the species as they move along the medium by differences in absorbance of the light. The volume of such zones is low, such as for example, 20 nanoliters.
Fraction collection such as a rotation table with containers on it have been used to collect separated fractions from separating devices. However, such prior art fraction collectors are not easily used for collecting fractions from capillary electrophoresis apparatuses for further use after initial absorbance detector assay because of the small volume of the sample components or zones within the capillary tube. Because the sample concentration within the zone may already be low, further dilution in the fraction collection process should be avoided. This is difficult to do as both the electrical ground connection and the capillary tube are immersed in a collecting electrolyte necessary to provide electrical continuity. This volume of electrolyte further dilutes the sample zone.